THE L3 SYSTEM — QUALITY CONTROL IN MANUFACTURE 



989 



the conditions encountered on two types of these capacitors which have 

 different capacitance tolerances. Studies indicate that the percentage of 

 the product faUing within the cell limits at the present time will vary 

 from 40 to 80 per cent depending on the capacitance value and tolerance. 

 Thus an expected merchandise loss of 20 to 60 per cent falling outside of 

 allowable tolerance exists which, in addition to the units classified but 

 not eligible to ship due to poor distribution of product among cells, 

 creates a condition resulting in increased cost of the product. It is ex- 

 pected, based on current methods and design, that the yield of the capac- 

 itors shipped ^vifchin the requirements of the distribution specification 

 will be between 20 and 70 per cent of the product manufactured. This 

 represents a situation in which the specification tolerances, the product 

 design, and the manufacturing process capabilities are not compatible, 

 but because of the design needs it is still necessary to meet the distribu- 

 tion requirements. The use of the three-cell method makes this possible 

 by the acceptance of relatively large shrinkages until improved manu- 

 facturing methods and materials now under investigation are introduced. 



CELLS 



13111^1 



44 45 46 47 48 49 50 51 52 53 



UNIT CAPACITANCE 



Fig. 9 — A summarized frequency distribution of a 43-inmf mica condenser at 

 various stages of manufacture. 



I 



